Browsing by Author "Minor M"

Now showing 1 - 4 of 4
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    Biochar increases soil enzyme activities in two contrasting pastoral soils under different grazing management
    (CSIRO Publishing, 2022-12) Garbuz S; Mackay A; Camps-Arbestain M; Devantier B; Minor M; Solaiman Z
    Context: Soil enzyme activities are key regulators of carbon and nutrient cycling in grazed pastures. Aims: We investigated the effect of biochar addition on the activity of seven enzymes involved in the carbon, nitrogen and phosphorus cycles in a Sil-Andic Andosol and a Dystric Cambisol under permanent pastures. Methods: The study consisted of a one-year field-based mesocosm experiment involving four pastures under different nutrient and livestock practices: with and without effluent under dairy cow grazing on the Andosol, and with either nil or high phosphorus fertiliser input under sheep grazing on the Cambisol. Soil treatments were: (1) willow biochar added at 1% w/w; (2) lime added at the liming equivalence of biochar (positive control); (3) no amendments (negative control). Key results: Compared with the Cambisol, the Andosol had higher dehydrogenase, urease, alkaline and acid phosphatase and, especially, nitrate-reductase activities, aligning with its higher pH and fertility. In both soils, biochar addition increased the activity of all enzymes, except for acid phosphatase and peroxidase; lime addition increased peroxidase and nitrate-reductase activity. Conclusions: The increased enzyme activity was strongly positively correlated with soil biological activity following biochar addition. Biochar caused a 40-45% increase in cellulase activity, attributed to increased root biomass following biochar addition. The response in acid and alkaline phosphatase activity can be attributed to the impact of biochar and lime addition on soil pH. Implications: The results provide more insights in realising the potential benefits of biochar to the provision of ecosystem services for grazed pastures.
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    CHANGES IN THE LEVELS OF THEILERIA ORIENTALIS IKEDA TYPE INFECTION IN HAEMAPHYSALIS LONGICORNIS NYMPHS OVER A SIX-MONTH PERIOD.
    (1/09/2021) Zhao Y; Lawrence KE; Minor M; Gedye K; Wang B; Pomroy W; Potter M
    This study aimed to investigate whether the infection intensity of Theileria orientalis Ikeda type organisms within Haemaphysalis longicornis larvae and nymph stages fluctuated over 6 mo after feeding as larvae on infected calves in the field. Naïve larvae, hatched from eggs, were fed on infected calves for 5 days while contained within cotton socks glued over the calves' ears. Larvae were first sampled immediately post-feeding and then sampled every 3 wk for 23 wk in total, after molting to nymphs. All larvae and nymphs were tested for T. orientalis Ikeda organisms using quantitative PCR. The qPCR results showed that the infection intensity of Haemaphysalis longicornis larvae and nymphs was not constant over the sampling period, and after initially dropping after molting to nymphs, it then rose with fasting to a maximum at 17 and 23 wk post-feeding. The significant rise in T. orientalis Ikeda organisms observed at 23 wk postfeeding may explain why more severe clinical cases of bovine theileriosis in New Zealand are seen in the spring when nymphs are the predominant instar questing.
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    Direct and indirect impacts of the Tuberolachnus salignus (Hemiptera: Aphididae) invasion in New Zealand and management alternatives
    (Published by Oxford University Press on behalf of Entomological Society of America, 2022) Tun KM; Minor M; Jones T; Clavijo-McCormick AC; Joyce A
    Invasive insects are a serious problem in New Zealand, and their introduction and successful establishment are predicted to increase with global commerce and climate change. A recent introduction to New Zealand is Tuberolachnus salignus (Gmelin), a large aphid that attacks mainly willows but also other plants such as poplars, apples, and pears. It was first reported in 2013 but has since then spread rapidly throughout the country. We conducted a 2-yr study exploring the direct (on the host plant) and indirect (on other organisms) impacts of the aphid, in a field setting including 15 willow clones selected to represent the variety of species and hybrids present in New Zealand. Our research revealed great variation in the level of resistance/susceptibility of different clones and suggested a trade-off between reproduction, growth, and defense. We investigated the indirect effects of the aphid on honeydew foragers and on the soil ecosystem, through honeydew production and deposition, revealing complex cascading effects involving multiple trophic levels. We also explore and discuss management alternatives including the replacement of willows for native species or resistant varieties, the use of biological control agents, and the feasibility of chemical control. This work is one of few studies on the complex ecological effects of invasive phytophagous insects and could serve as a model for future research and to inform pest management. To conclude, we identify gaps in the knowledge and highlight aspects requiring further research.
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    Regenerative agriculture in Aotearoa New Zealand - research pathways to build science-based evidence and national narratives.
    (2021-02-22) Grelet G; Lang S; Merfield C; Calhoun N; Robson-Williams M; Horrocks A; Dewes A; Clifford A; Stevenson B; Saunders C; Lister C; Perley C; Maslen D; Norton D; Selbie D; Chan D; Burns E; Le Heron E; Crampton E; Curran-Cournane F; Doolan-Noble F; Griffin F; Good H; Pinxterhuis I; Todd J; Vernon J; Su J; Cavanagh J; Laubach J; King J; Jones J; Orwin K; MacMillan K; Minor M; Anderson M; Buckley M; Harcombe M; McGlone M; Davidson M; Barry M; Taitoko M; Kirschbaum M; Donovan M; Conland N; Stanley-Clarke N; Masters N; Schon N; Mason N; Gregorini P; Mudge P; Tapsell P; Bruce-Iri P; Tait P; Roudier P; Mellor R; Teague R; Gregory R; Price R; Holdaway R; Dynes R; Lavorel S; O'Connell S; Letica S; Belliss S; McNeill S; Apfelbaum S; Driver T; Fraser T; Baisden T; Kerner W